QSAR - RE: electron density based superposition (Andras.Borosy===givaudan. com)

Overlaying crystallographic electron density maps is being researched but
only the valence electron overlays are usually of interest. Density maps are
a conglomeration of all the electron shells and tend to swamp the valence
shells. Consequently, overlays are not precise enough to be used as
comparators. MEP contour maps are an alternative but are difficult to
overlay. Distilling these down to their electrostatic extrema results in a
tractable solution (Vinter 1987 and Price 1994). However, MEPs derived from
atom-centred charges (used by nearly all MD and MM methods) are poor
compared with those from QM/DMA. A new force field has been created which
extends electrons away from the nucleus and results in a much improved
electrostatic description of molecules and accurate MEP extrema. Cresset-BMD
(www.cresset-bmd.com) has created extrema patterns of 2.5M commercially
available molecules to construct a database that can be searched with a
template extrema pattern in a very short time.
The answer to the question Andras has posed is 'no' for X-ray-derived
electron density maps but 'yes' for molecular electrostatic potentials.

Dr Andy Vinter
Chief Scientific Officer
Cresset Biomolecular Discovery Ltd
United Kingdom
t: +44 (0)1462 476320
e: andy++cresset-bmd.com
 
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Today's Topics:

   1. electron density based superposition (Andras.Borosy===givaudan.com)

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Message: 1
To: "Computational Chemistry List" <chemistry-request###ccl.net>
From: Andras.Borosy]^[givaudan.com
Date: Fri, 23 Jan 2004 13:12:17 +0100
Subject: QSAR - electron density based superposition
Reply-To: qsar_society-.-accelrys.com

Dear Colleagues,

Does a (validated) computer application exist which can align molecules=20
based on their electron density?

Many thank,

Andr=E1s Borosy
PhD Computational Chemist
Givaudan Schweiz AG
Fragrance Research
Ueberlandstr. 138
8600 D=FCbendorf
Switzerland
tel: + 41-1-8242164
fax: +41-1-8242926
e-mail: andras.borosy**givaudan.com

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Received on 2004-01-26 - 12:32 GMT